image: The water-poor zwitterionic hydrogel regulates the local water environment, stabilizes zinc deposition and limits polyiodide migration. The figure also compares ionic conductivity and operating temperature windows with previously reported electrolyte systems.
Credit: ©Science Bulletin
Aqueous zinc–iodine batteries have attracted increasing attention for large-scale energy storage due to their low cost, high safety, and environmental compatibility; however, parasitic reactions caused by water activity, zinc dendrite growth, iodine species migration, and performance degradation under extreme temperatures remain major challenges.
The research team developed a water-poor zwitterionic hydrogel electrolyte by integrating zwitterionic groups and hydrophilic polymer networks, while partially replacing water with glycerol to regulate water activity without sacrificing ionic transport.
Spectroscopic analyses and simulations revealed that glycerol and polymer chains reorganize the hydrogen-bond network and regulate the Zn2+ solvation structure, enabling uniform zinc deposition, stable interfacial layer formation, and effective suppression of iodine species migration through electrostatic confinement.
Based on this electrolyte design, the Zn–I2 batteries achieved robust cycling performance across an ultrawide temperature range from −40 to 90 °C, demonstrating excellent durability in high-rate cycling and pouch-cell configurations.
This work provides a molecular-level electrolyte engineering strategy that simultaneously regulates water activity and stabilizes both electrodes, offering new opportunities for developing aqueous energy storage systems capable of operating under